1. Field of the Invention
The present invention relates to a resource allocation method of a wireless communications system, and more particularly, to an efficient resource allocation request method in a wireless system comprising a base station and a plurality of terminals.
2. Description of the Related Art
Wireless communications systems have been developed into a second-generation system, a third-generation IMT 2000 system, and a fourth-generation wireless asynchronous transfer mode (ATM) system, etc.
As shown in FIG. 1, a wireless communications network manager segments a service area into cells and operates base stations 40 and 60 so that subscriber terminals 41, 42, 43, 55, 61, and 62 can use a given wireless frequency resource.
The subscriber terminals 41, 42, 43, 55, 61, and 62 in the service area request the base stations 40 and 60 to allocate the resource. The base stations 40 and 60 must allocate the resource so that as many subscribers as possible can communicate with high quality.
A frequency resource is allocated differently according to the particular communications system. That is, a specific carrier frequency is allocated to each of the subscribers in a cell in a frequency division multiple access (FDMA) system, a specific time slot for a carrier frequency is allocated to each of the subscribers in a time division multiplex access (TDMA) system, and a specific code is allocated to each of the subscribers in a code division multiple access (CDMA) system.
The wireless communications system requests resource allocation in various situations. For example, when a cellular subscriber makes a telephone call or transmits a file, resource allocation is requested, and when a subscriber 55 on the telephone using an already-allocated resource moves from a specific cell to another cell, allocation of a new resource is requested to prevent the conversion from being interrupted. When the subscriber moves to a cell controlled by an adjacent base station while talking on the phone, a subscriber""s terminal receives a strong signal from the adjacent base station and generates handoff.
In particular, in a CDMA cellular system using the same frequency band between cells, when a terminal moves to an adjacent cell, handoff is generated in an area where a strong signal is received from the adjacent cell.
A method of effectively allocating a resource in this wireless communications system has been disclosed in xe2x80x9cCongestion Control System and Method For Efficient Multi-frequency Messagingxe2x80x9d by J. H. Lin et al. (U.S. Pat. No. 5,740,533), and xe2x80x9cSystem and Method For Providing Priority Access and Channel Assignment In a Cellular Telecommunication Systemxe2x80x9d by R. S. Joseph et al. (U.S. Pat. No. 5,574,977).
When several terminals request resource allocation from a base station at the same time, the probability that occurences of a collision between the requests of terminals increases. Therefore, a resource allocation request algorithm and a method of solving the problem of collision have been proposed in standards such as group special mobile (GSM), IS-95, and IEEE802.11, among others.
Referring to FIG. 2, when a terminal (a) in step 202 receives an application command such as a command for making a telephone call or for transmitting a file, corresponding to a resource allocation request from a user, a call request packet is transmitted to a wireless base station (b) in step 203. Then, the wireless base station (b) inspects a parameter of the received call request packet in step 302, and a decision of whether resource allocation will be made is made in step 303. Here, the wireless base station (b) performs a resource allocation decision algorithm and sends a message indicating failure or success of resource allocation to the terminal (a). The terminal (a) initiates a communications service when a message indicating successful resource allocation is received from the wireless base station (b), in steps 204 and 205.
However, even by applying these wireless resource allocation standards, several terminals requiring resource allocation may perform a resource allocation request simultaneously without information associated with the present conditions of a resource.
Thus, the requests of these terminals are highly likely to collide with one another. Even if no collision occurs, there may not be wireless resources that can be allocated to terminals. As a consequence, resources cannot be effectively utilized.
To solve the above problem, it is an objective of the present invention to provide an efficient wireless resource allocation method in which a base station broadcasts all resource information being used in a cell controlled by the base station, and terminals variably request the base station to allocate resources according to the resource information, in a wireless communications system.
Accordingly, to achieve the above objective, there is provided a resource allocation request method in a wireless communications system including a plurality of base stations and a plurality of terminals, the method comprising the steps of: periodically broadcasting resource information managed by the base stations to the terminals; receiving and storing the periodically-broadcast resource information in the terminals; making a determination in response to a resource allocation request by comparing a parameter value of a resource, extracted from the stored resource information, with a preset critical value when a terminal receives an application command corresponding to a resource allocation request from a user; and variably requesting resource allocation of the base stations according to the determination of the terminals in response to the resource allocation request.